Fang, Dong

Abstract [en]

The consuming of paper and fibrous products is nowadays tremendous in our daily life. The raw material used in the paper industry is mainly wood fibers. A better understanding of properties of these fibers will help to improve the performance of the paper industry. Fiber deforms with time when subjected to a load, which has to be compensated for in packaging materials by the use of thicker papers thus more material. This deformation increases in the variable climate. This well-known complex phenomenon is called mechano-sorptive creep and leads to large losses in the paper industry every year.

In order to understand the influence on the creep phenomenon of different fiber morphology, and how and to what extent the fibril angle affects the mechano-sorptive creep, the creep behavior of four series of fibers from spruce were measured by DMA (Dynamic Mechanical Analyzer) at a constant humidity climate followed by an immediately cyclic humidity. The fibers used were mature latewood fibers, mature earlywood fibers, juvenile latewood fibers and juvenile earlywood fibers. The CLSM (Confocal Laser Scanning Microscopy) was used to determine the microfibril angle of the fibers. The results of the tests show a higher creep rate at cyclic humidity than that at constant humidity. The comparisons among fibers show that latewood fibers have higher mechano-sorptive creep ratio (creep rate at cyclic humidity/ creep rate at constant humidity) than earlywood fibers and that juvenile wood fibers have higher creep ratio than mature wood fibers. One of the main conclusions drawn in this study was that the higher the fibril angle, the lower was the mechano-sorptive creep ratio.